Affiliation: | (1) Department of Mathematics, Peking University, Beijing, China;(2) Institut für Mechanik, Ruhr-Universität Bochum, Bochum, Germany;(3) Department of Mechanics, Zhongshan (Sun Yatsen) University, Guangzhou, China;(4) Department of Mathematics, University of Kentucky, 40506-0027 Lexington, Kentucky, USA |